The Metabolism Core is designed to conduct in vivo and physiological experiments in conscious mice for the purpose of detailed metabolic phenotyping of transgenic mouse models useful for understanding obesity, diabetes and its complications. The Core operates under the supervision of Drs. Jason Kim (Director), Dae Young Jung (co-Director), and Hwi Jin Ko (co-Director) who oversee day-to-day operation of the Core and interact with the users of the UMass MMPC. The principal functions of the Core are to perform the following experiments: 1) hyperinsulinemic-euglycemic clamp to assess organ-specific insulin action and glucose metabolism in conscious mice, 2) hyperglycemic clamp to assess in vivo pancreatic beta-cell function in conscious mice, 3) iv or ip glucose/insulin tolerance tests, 4) survival surgery of jugular vein cannulation for in vivo experiments, 5) implementation of osmotic pumps for chronic delivery of drugs or other agents, 6) application of special diet (e.g.. high-fat diet) to alter energy balance and induce obesity in mice. 7) acute lipid infusion, acute/chronic delivery of cytokines and phloridzin, and STZ injection to alter glucose homeostasis. 8) non-invasive measurement of energy expenditure, respiratory exchange ratio, physical activity, and food/water intake in conscious mice using metabolic cages. 9) non-invasive assessment of whole body, organ, and tissue biopsy composition of fat/lean/water mass in conscious mice using 1 H-MRS. 10) implementation of cage wheel for exercise study, and 12) biochemical analysis for intracellular metabolic flux measurement (glycolysis, glycogen synthesis). The Metabolism Core regulariy interacts with the Analytical Core for complementary, high-throughput analytical assays to measure hormones, cytokines and metabolites using serum samples obtained at the end of metabolic experiments. Also, the Metabolism Core interacts and with the Cardiovascular Complications Core for additional phenotyping associated with cardiovascular functions. The goal of the Metabolism Core is to use an array of elegant, non-invasive and in vivo experiments to obtain a robust set of metabolic data from individual mouse in order to provide mechanistic insights into the role of selected gene on obesity, insulin resistance, and diabetes.